There are several types of microswitches. The prior art microswitch shown in FIG. 5 has a movable contact 51 which is provided at an end of movable piece 54. The other end of the movable piece 54 is fixed at an end of holding piece 53. The movable piece 54 can swing around the holding piece 53 which is a portion of a common terminal 52. Fixed contacts 55 and 56 are connected to fixed terminals 57 and 58, respectively. A coil spring 60 is provided between standing member 59 and a middle portion of movable piece 54. A push-button 61 is disposed to push the coil spring 60 in the free position of the switch, wherein the movable contact 51 is on the upper fixed contact 55. If the push-button 61 is pressed down the coil spring 60 is distorted downwardly so that the movable piece 54 is clicked down around the other end to make the movable contact 51 with the fixed contact 56, thus, performing a switching operation.
FIG. 6 shows another type of conventional microswitch. A movable piece 64 has a movable contact 62 and a movable plate spring 63, one end of which rests on a holding piece 69 which is made in one piece with a common terminal 70. Fixed contacts 65 and 60 are connected to fixed terminal 67 and 68, respectively. Push-button 72 is provided to push receiving member 71, both ends of which are connected to common terminal 70 and the end portion of movable piece 64. In the free position of this switch a movable contact 62 rests on fixed contact 65. When push-button 72 is pushed down, the end of movable piece 64 is moved downwardly through the receiving member 71. When movable piece 64 passes over a certain point, movable plate spring 63 turns around to make its movable contact 62 with fixed contact 60.
The switch shown in FIG. 5 is simple in construction, but in its switching operation, movable piece 54 swings around a holding piece, so that a wiping effect by movable contact 51 cannot be expected. The wiping effect of movable contact 51 is necessary for avoiding the welding of contacts often observed in this type of high-capacity switch. More specifically, an arc flows between contacts when a switch makes and breaks to weld the contacts. Wiping is required to remove melted substance from the surface of contacts and to improve the reliability of switch operation. On the other hand, in the switch shown in FIG. 6, the swinging point of receiving member 71 is located under the conjunction point of receiving member 71 and movable piece 64, so that when pushbutton 72 is pressed down, the movable piece 64 moves a little bit backward. Therefore, when the movable contact 62 comes away from fixed contact 65, it can have a wiping effect on the fixed contact 65. However, this type of switch needs receiving member 71, which makes the structure more complicated.
The actuator 18 which is positioned to cover the push-button 12 can be modified as shown in FIGS. 7-9. Initially, however, an actuator in the prior art has been illustrated in FIGS. 10-11. Shown in FIG. 10 is a switch having a switching mechanism contained in case 101 which has a push-button 102 and an actuator 103 for pressing on the button 102. The actuator 103 is a metal plate, a portion of which is folded downwardly to form a regulating member 104. A pair of actuator portions 105 are formed as supporting members for the actuator 103, while the other end of the actuator 103 is folded to form a pair of roller supporting members 109. Both sides 101B of the case 101 have cuts 101D at the corners of case 101. A pin 106 is formed with one piece with the case 101 to permit the supporting members 105 to be rotatably engaged. A roller 108 has a rotary shaft 107 which is coupled to roller supporting member 109. The actuator 103 which is rotatably supported by the pin 106 is positioned over the push-button 102. Normally, the actuator 103 is held up by the restoring force of the push-button 102. When an object hits the roller 108, the actuator 103 moves around pin 106 and pushes the push-button 102 against its restoring force, thus, operating the contact switching mechanism housed within the case 101. After the depressing force is removed from the actuator 103, the actuator 103 is instantly raised by the restoring force of push-button 102. When the actuator 103 rotates, the regulating member 104 contacts side 101C of the case 101 in order to stop the rotation of the actuator 103. However, the regulating member 104, as shown in FIG. 10, has problems adjusting the rotation of the actuator 103 due to an unstable folding angle. Moreover, when the actuator 103 is held up in a forceful manner, the regulating member 104 is pressed against side 101C of the case 101, thereby, distorting the regulating member 104. Therefore, the switch illustrated in FIGS. 10 and 11 is highly unreliable.
To solve the above-discussed problems, especially concerning the lever portion of the switch, this invention further provides a switch having a regulating member for rotating an actuator which can be manufactured with significant accuracy. Moreover, the switch of the instant invention is highly capable of maintaining it reliability during operation.
One feature of this invention is a switch with a simple structure and which has an improved life span because of the wiping of the surfaces of contact. Moreover, the switch of the instant invention comprises a switch having an outwardly protruding push-button for operating a contact switching mechanism housed within the case. Further, there is in this invention an actuator having at one end a pair of supporting members folded downwardly and rotatably engaged with the case, whereby the other end of the actuator is a free end. The supporting members of the actuator are formed in one piece with the regulating member which contacts one side of the case in order to stop the rotation of the actuator.